Gabriel Blackstone is a cool, hip, thoroughly 21st Century Londoner with an unusual talent. A computer hacker by trade, he is - by inclination - a remote viewer; someone whose unique gifts enable him to see into the thought processes of others.

But he only does this with the greatest reluctance - until he is contacted by an ex-lover who begs him to use his gift to find her step-son, last seen months earlier in the company of two sisters.

And so Gabriel visits Monk House in Chelsea, a place where time seems to stand still. Its living room is filled with the perfume of roses, African masks line the walls and everywhere - on doors, on walls, on ceilings even - the mysterious coded symbol of cross and circle dominates.

As the dog days of summer turn into a cold and hostile winter, Gabriel becomes increasingly bewitched by the house, and by its owners, the beautiful, enigmatic Monk sisters - one of whom is a deadly killer, and who will stop at nothing to protect a terrifying secret that is as old as time itself.